lightnvm: rename gennvm and update description

The generic manager should be called the general media manager, and
instead of using the rather long name of "gennvm" in front of each data
structures, use "gen" instead to shorten it. Update the description of
the media manager as well to make the media manager purpose clearer.

Signed-off-by: Matias Bjørling <m@bjorling.me>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/lightnvm/Kconfig

@@ -27,11 +27,13 @@ config NVM_DEBUG
 	It is required to create/remove targets without IOCTLs.
 
 config NVM_GENNVM
-	tristate "Generic NVM manager for Open-Channel SSDs"
+	tristate "General Non-Volatile Memory Manager for Open-Channel SSDs"
 	---help---
-	NVM media manager for Open-Channel SSDs that offload management
-	functionality to device, while keeping data placement and garbage
-	collection decisions on the host.
+	Non-volatile memory media manager for Open-Channel SSDs that implements
+	physical media metadata management and block provisioning API.
+
+	This is the standard media manager for using Open-Channel SSDs, and
+	required for targets to be instantiated.
 
 config NVM_RRPC
 	tristate "Round-robin Hybrid Open-Channel SSD target"